Need to repaint a house trailer with textered alum siding. Washing is not an option because there is no windows or weatherstripping so any water will get into the walls. Current paint is less than paper thin and already has been sanded and painted about 4 times already in one place. (Not by me but I was present. It doesn't look good.)
I have a few questions for the seansoned pros,
1. What are good grits to sand with on a 6" D.A. orbital?
2. How do I properly clean the metal for primer?
3. Do I go with a self etching or primer sealer?
4. I've read to stay away from laquer based paints. What do I go with?
5. First time running a spray gun so How do I attempt this?
6. Mixing....Self explanitory.
7. Finishing the job. What grit, How to wetsand, What pattern to use, Etc...
8. Prepping, Duration, and finishing in general.
9. Masking and what types of tape.

I have a 33 Gal. Craftsman 2HP running 6 Developed 6.4 SFCM compressor and a Cambell Hausfel spray gun.

Trailer deminsions are 8' wide 7' tall 29' long. This will have to be on a budget. Not sure how much. I gave up on trying to patch a shot factory paint job with spray bombs. Primer kept vinalising (sp?) and white would keep running. Used rustoleum products. Never had a problem with them before until now.

I know its alot but I need the help. Thanks guys.

 

Good luck with your project! I'll try to offer some advice but, my painting is limited to aircraft and I know there is bound to be differences. With any luck someone can help to make it all fit for what you're trying to do. Here goes.

1. What are good grits to sand with on a 6" D.A. orbital? Anything harsher than 220 grit can end up laving score marks that may require more coats (read, more money) of paint to cover. Plus, if it's textured, you might have better luck taping off the open areas and media blasting it or using a paint stripper. They do have paint removing chemicals that work on aluminum, but you have quite a large project...

2. How do I properly clean the metal for primer? Once the metal has been stripped, a good clean with mild soap and water will work. Actually, a good test of aluminum surface cleanliness is how well water rolls off it. A final wipedown with a rag dampened with dry cleaning solvent is fantastic. Rubbing alcohol works too, but can sometimes leave a residue (which causes a LOT of paint separation/run-off problems). A corrosion preventive chemical called alodine is a pretreatment for aluminum, but is not necessary. (if you can even find it) Basically, once it is clean and dry, you're good to go.

3. Do I go with a self etching or primer sealer? I would say absolutely go with a quality primer, but I'm not the best guy to recommend which one.

4. I've read to stay away from laquer based paints. What do I go with? Polyurethane paints work very well for aluminum.

5. First time running a spray gun so How do I attempt this? ALWAYS, test your spray pattern, even if you've only stopped spraying for a few moments. Adjust it to coat effectively for your speed and distance (everyone varies a little) Keep it within 12 inches for decent results. The spray pattern will look like a () meaning it should come out tall and narrow. Always spray a couple inches beyond your work as you make passes back and forth (this helps ensure an even spray coating that can sometimes be too thick or thin at the edges) Be prepared for overspray and try to avoid spraying in the wind, dusty conditions or direct sunlight. Your surface should be comfortable, too hot and paint can sort of pill up or separate or all sorts of other nastiness. Too cold and your can get more running and longer cure times.

6. Mixing....Self explanitory. Yes, follow directions carefully.

7. Finishing the job. What grit, How to wetsand, What pattern to use, Etc... Not really my area, sorry.

8. Prepping, Duration, and finishing in general. Take your time! The key to a successful paint job is good preparation. Get it as clean as you can, mask it off carefully, wait for the right conditions to spray, do not rush your spray job. If your paint is setting up too fast or your gun is giving you problems, STOP, clean the gun, mix new paint, check and recheck your spray pattern and keep an eye on air pressure. Once you get the hang of it, you'll have a blast.

9. Masking and what types of tape. 3M can be a bit pricy but they have an excellent blue painters tape. Whatever tape you use, just ensure it is adhering well. A poor tape job can let the paint edges look like garbage. Also, don't leave the tape on any longer than you have to. Some tapes, when left on too long can leave a lot of residue when they are removed. It's an absolute pain.

I have a 33 Gal. Craftsman 2HP running 6 Developed 6.4 SFCM compressor and a Cambell Hausfel spray gun.

Trailer deminsions are 8' wide 7' tall 29' long. This will have to be on a budget. Not sure how much. I gave up on trying to patch a shot factory paint job with spray bombs. Primer kept vinalising (sp?) and white would keep running. Used rustoleum products. Never had a problem with them before until now.

I know its alot but I need the help. Thanks guys.[/quote]

Remember to take the time and prep it well. If you have the patience, you will be rewarded. Like I said, I paint aircraft, I'm positive someone can help out with the things I may have missed. Good Luck! And wear a respirator!

 

WOW! Thanks alot! That really helps!
On the resperator part, I shouldn't be able to smell anything through it should I?

 

It depends on the type. A face mask, like a doctor might wear will allow scents but can keep out larger particles. (not the best) A "half-face" respirator with good filters should keep you from smelling anything. When we "fit test" our respirators, we commonly use banana oil. If you can taste or smell sweetness, it doesn't fit right.

Here's an example of a great respirator for painting.

<http://www.amazon.com/3M-Low-Maintenance-Half-Mask-Respirator-Assembly/dp/B00004Z4EB/ref=sr_1_5?ie=UTF8&qid=1361942857&sr=8-5&keywords=3m+half+face+respirator>

There are organic filters (cartridge style) and simple round cloth/fiber dust filters. they can be doubled up and work the great. The cartridge filters alone are plenty. They have exposure limits, so get two pair, just in case.

P.S. I'm not trying to push 3M products. lol. They just happen to be what I work with most so they are an easy example for me to use. Shop around and go with what works best for you.

 

What I'm using a 3M one with whats called a easy breathe valve. It is a half face one. When I first started using it, It worked great. Now, hardly and its not even a week old.

On the sanding, Do I need to take it down until the alum is bare or just until it is smooth? The factory paint has no primer under it or it is white also.

 

Most of the respirators I work with have filters that have exposure limits like 8 hours max. Also, once a filter has been exposed, it will start to break down and lose efficiency, even if it isn't being constantly exposed. Filter replacements, that's how they get ya. Also keep an eye on the outlet valve. It doesn't take much to keep those little suckers from sealing well.

 

^^^ +1 on that advice! Owned a body shop back in the 80's and began requiring all painters to use minimum half-mask respirators. Equipped each with a Tupperware bowl large enough to hold the cartridges when not in use. We also decided proximity to paint supplies would be maximized to reduce exposure too.

Like so many others they assumed as long as they could still suck air through them they'd do their job. Once we were made aware of the 8 hour exposed life expectancy most painters took better care of their equipment.

 

Sorry, I didn't notice this part earlier. Technically, you can take the paint down to a "good' prepped surface and spray it. However, it isn't always the best idea. The old paint may be beginning to delaminate from the aluminum surface and so, your new paint would simply flake off with it when it finally goes. This can happen from corrosion on the surface which has not been identified or if there is too much contaminant in the old paint. Paints are very effective at sealing out elements but are not absolutely non-porous and so over the years, gunk gets in. If there is oil or some other sort of contaminant, it can also affect the way the paint looks. It can cause separation, bleed through, "orange peel" as well as adhesion problems. I guess it goes back to good preparation being the key to a good paint job. It's not the funnest way to go about it, but it is a wiser choice to remove as much of the old paint as you can. If there is some left, clean the surface as best as you can with mild soap and water, and perhaps a wipe down with dry cleaning solvent or acetone. It will help remove any leftover dirt or residue. I know you mentioned having a textured aluminum surface so that has to come into account when balancing prep work with the amount of time spent going "too far" to get the last bit of paint off.

 

Yeah, I can go too far but it is going to take FOREVER and alot of sandpaper and money. Once I get down past the old junk and gunk, The paint is clean and smooth. Then after that is bare metal.